bugfix: cast to storage type if defaultValue is a reference

otherwise if you have a `string` field, and provide a `type Value string`-valued default, you get an error trying to assign an alias to a string

Author: alexzielenski

examples/defaulter-gen/generators/defaulter.go

@@ -565,6 +565,7 @@ func populateDefaultValue(node *callNode, t *types.Type, tags string, commentLin
 
 	node.defaultIsPrimitive = baseT.IsPrimitive()
 	node.defaultType = baseT.String()
+	node.defaultTopLevelType = t.Name
 	node.defaultValue.InlineConstant = defaultString
 	node.defaultValue.SymbolReference = symbolReference
 	node.defaultDepth = depth
@@ -812,7 +813,7 @@ func (g *genDefaulter) GenerateType(c *generator.Context, t *types.Type, w io.Wr
 
 		}
 
-		for i, v := range current.defaultDepth {
+		resolveTypeName := func(v types.Name) types.Name {
 			var prefix string = ""
 
 			// Check for pointer. If it is a pointer type, resolve the element
@@ -827,15 +828,21 @@ func (g *genDefaulter) GenerateType(c *generator.Context, t *types.Type, w io.Wr
 
 			if len(v.Name) > 0 && len(v.Package) > 0 {
 				if g.isOtherPackage(v.Package) {
-					current.defaultDepth[i] = types.Name{
+					return types.Name{
 						Name: prefix + g.imports.LocalNameOf(v.Package) + "." + v.Name,
 					}
 				} else {
-					current.defaultDepth[i] = types.Name{
+					return types.Name{
 						Name: prefix + v.Name,
 					}
 				}
 			}
+			return v
+		}
+
+		current.defaultTopLevelType = resolveTypeName(current.defaultTopLevelType)
+		for i, v := range current.defaultDepth {
+			current.defaultDepth[i] = resolveTypeName(v)
 		}
 
 		if len(current.call) == 0 {
@@ -932,6 +939,10 @@ type callNode struct {
 	// defaultType is the type of the default value.
 	// Only populated if defaultIsPrimitive is true
 	defaultType string
+
+	// defaultTopLevelType is the final type the value should resolve to
+	// This is in constrast with default type, which resolves aliases and pointers.
+	defaultTopLevelType types.Name
 }
 
 type defaultValue struct {
@@ -1102,7 +1113,12 @@ func (n *callNode) writeDefaulter(varName string, index string, isVarPointer boo
 			args["defaultZero"] = defaultZero
 
 			sw.Do(fmt.Sprintf("if %s == $.defaultZero$ {\n", variablePlaceholder), args)
-			sw.Do(fmt.Sprintf("%s = $.defaultValue$", variablePlaceholder), args)
+
+			if len(n.defaultValue.SymbolReference) > 0 {
+				sw.Do(fmt.Sprintf("%s = %s($.defaultValue$)", variablePlaceholder, n.defaultTopLevelType), args)
+			} else {
+				sw.Do(fmt.Sprintf("%s = $.defaultValue$", variablePlaceholder), args)
+			}
 		}
 	} else {
 		sw.Do(fmt.Sprintf("if %s == nil {\n", variablePlaceholder), args)